The present invention relates to network management and particularly, although not exclusively to management of a communications network.
A conventional communications network, for example a broadband communications network comprises a plurality of physical resources, eg switches, cross connects, regenerators, repeaters, transmission links such as fiber optic links or coaxial cable links, operating under control of a plurality logical resources, eg transport protocols, and local controls associated with individual physical resources. An example of a generic representation of a communications network is illustrated in FIG. 1 herein, in which the physical resources are located at a plurality of nodes 100 and links 101 distributed over a geographical area. For a network operator to maintain control of a communications network for its operation, administration and maintenance, a management information base is maintained which stores information describing the physical and logical resources within the network. One or more management information bases may reside at a centralized location, eg a network controller 102, or different information bases may be situated at a plurality of network controllers at different locations. The management information base contains data describing each individual network element in a communications network. A conventional communications network may comprise of the order of hundreds of individual network elements, eg switches, cross connects, regenerators, each of which contains of the order of tens to hundreds of cards, having processors, line terminations, buffers, registers, switch fabrics, etc. each card containing of the order of hundreds of individual components. In general, a conventional communications network may comprise a multitude of different legacy equipment types of different proprietary manufacture, each of which has its own particular internal configuration and offers its own specific capabilities.
The International Telegraph and Telephone Consultative Committee (CCITT) of the International Telecommunications Union (ITU) in their recommendation G.774 published September 1992 (available from International Telecommunication Union, General Secretariat, Sales Service, Place de Nation, CH 1211, Geneva 20, Switzerland), specifies a recommended architecture of an information model for synchronous digital hierarchy (SDH) networks. In recommendation G.774, there is specified a model which describes managed object classes and their properties which are useful for describing information exchanged across interfaces defined in recommendation M.3010, telecommunications network management (TMN) architecture, also of the ITU-T. Recommendation G.774 identifies the telecommunications management network (TMN) object classes required for the management of SDH network elements, and specializes the generic object classes presented in recommendation M.3010 to provide management information specifically for synchronous digital hierarchy. These objects are relevant to information exchanged across standardized interfaces defined in recommendation M.3010 TMN architecture. In recommendation G.774, network resources are modeled as objects and a management view of a resource is referred to as a managed object. Objects with similar attributes may be grouped into object classes. An object is characterized by its object class and object instance, and may possess multiple attribute types and associated values. Object classes defined in recommendation G.774 apply to various management areas, for example fault management and configuration management. However, the inventors have experienced that the ways in which information is conveyed in accordance with methods specified in recommendation G.774 have several inadequacies.
Firstly, under conditions of equipment start-up, large amounts of data are transferred across the network, using up capacity on the operation administration and maintenance (OAM) channels. For example, for a network element having a shelf containing 25 line cards, on start-up each line card transmits enrol data describing each of the termination points on that line card, as well as data describing the relationships between the termination points on that line card. Every time the shelf is started up, the same termination point enrol data and relationship data is transmitted across the OAM channel to the management information base. For successive start-ups of the shelf, the enrol procedure is repeated, transmitting the same information on every start-up. Similarly, on starting up an identical shelf, the same enrol data is transmitted to the management information base, every time that other shelf is started up. Thus, under conditions of network fault, when a plurality of network elements are restarted, the whole enrol procedure for each network element is repeated. However, the information transmitted is basically static, ie the same as the information which was transmitted last time the shelf was started up.
Some prior art systems have addressed the problem of large data volumes on the OAM channel by operating on a principle of Assumed Management Knowledge. In these cases, a network manager assumes that certain network elements have certain capabilities and that they operate in a particular way. This avoids having to explicitly elicit the actual information concerning the operation of the elements from the elements themselves, or from another source in the network, since obtaining such information would cause a high level of management traffic. One consequence of the assumed knowledge system is that assumptions may be erroneous and the network elements may operate in a way different to that assumed, leading to network management errors or less than optimal management of specific network elements, and of the network as a whole.
Secondly, the recommended management information model G.774, although providing for description of the content and configuration of a physical resource, does not adequately accommodate description of the capabilities of that physical resource. In particular, recommendation G.774 assumes potentially infinite flexibility of configuration of a described physical resource, whereas in practice there are practical limitations on the possible configurations of a resource. For example, physical resources may be subject to hard wired restrictions as a result of restrictions in an application specific integrated circuit (ASIC). Thus, irrespective of the way in which the physical resource is modeled in an information base, physical limitations on connectivity of the physical resource may exist. As an example, consider a physical resource having four ports numbered 1 to 4. Ports 1 and 2 may be capable of connecting with each other and to a further port, port 4. However, ports 1 and 2 may be incapable of connecting to port 3 due to a hard wired restriction on connectivity in the resource. However, recommendation G.774 does not provide a way of expressing such connectivity restriction, but assumes any port of the physical resource can be connected to any other port of the physical resource. Recommendation G.774 does not provide for description of such inherent capability restrictions in a physical resource.
One object of the present invention is to provide an improved means for initialization of a management information base upon start up of physical resources in a network.
Specific methods according to the present invention may provide a means of increasing a flow of management information between a plurality of network elements and a management system, but using a lower amount of data transfer between the network elements and the management information base.
Another object of the present invention is to provide a means of conveying information concerning capabilities of physical resources to a management information system.
Specific methods according to the present invention may provide a means of describing capabilities of a physical resource which encompasses an unlimited range of possible capabilities, but which is also capable of describing specific limitations on capability within specific network element types.
According to one aspect of the present invention there is provided in a communications network comprising a plurality of network elements, a method of providing management data describing available capabilities of a said network element, said method comprising the steps of:
representing resources of said network element by at least one data template representation; and
referring to said data template representation by means of a message generated by said network element.
In a preferred implementation, said messages are communicated over an operations, administration and management channel of said communications network. The messages may provide an efficient means of compression of information transmitted over an OAM channel.
Preferably, said step of referring to said data template representation comprises the steps of:
representing each of a plurality of end points of said network element by a corresponding respective end point data, each said end point data comprising a reference to at least one said data template representation.
A said data template representation may comprise data describing a plurality of protocol layers operated by a said physical resource.
The physical resources suitably comprise a plurality of end points at which data packets, cells or frames may emerge or sink. The end points may comprise a physical or logical port. The physical resources suitably comprise a set of pre-configured structures, eg of layered termination points connected into end points.
Preferably, said step of representing resources by at least one data template representation comprises the step of representing connectivity capability between a plurality of ports of a said network element by a said data template representation.
Said step of representing resources of said network element by at least one data template representation may comprise the step of representing connections capability between a plurality of ports of said network element at a same layer as each other by a set of connection rules describing inter-port connections.
A set of said connection rules at a same layer may be collected into a connection group.
Said step of representing resources of said network element by at least one data template representation may comprise the step of representing connection capabilities between individual ports of a plurality of ports of said network element by a set of connection rules between said groups.
Suitably, each said port is represented by a corresponding respective end point data.
A said message may comprise a plurality of said end point data, each end point data representing a corresponding respective end point.
The invention includes a management system for managing a network element comprising a plurality of physical resources arranged into a plurality of pre-configured structures each of a pre-configured structure type, said management system comprising a data storage storing:
at least one data template, said data template representing a said pre-configured structure; and
a plurality of reference data, each said reference data referring to a said pre-configured structure and to at least one said data template.
According to a second aspect of the present invention there is provided a data representation of a physical resource operating in accordance with a protocol having a plurality of layers, said resource comprising at least one termination point in a said layer, at least one adaptation capability for adapting between said layer of said termination point and a client layer, and a connection capability for connecting said termination point, said data representation comprising:
termination point data describing a said termination point within a said layer;
adaptation rule data describing adaptation rules between said layer and a further layer; and
connection rule data describing connection capabilities of said termination point.
Preferably, said connection rules describe connection capabilities of said termination point within a same layer as said termination point.
Said connection rules may describe connection capabilities of said termination point to a layer other than a layer of said termination point.
Preferably, said termination point data comprises data describing a type of termination point.
Preferably, said adaptation rule data comprises data describing a relationship to a next rule in a logic list.
Characteristics of said termination point other than its layer may be stored in a sub-type of said termination point data component.
Said sub-type is preferably implemented as an ASCII field. Said template may be implemented in UNIX external data representation (XDR) language. Said template may be implemented in common object related broker architecture interface definition language (CORBA IDL). Said template may be implemented in ASN1 GDMO, simple network management protocol (SNMP), JAVA, or C+ structure definitions.
Preferably, said adaptation data component comprises data describing a transport protocol. For example, said transport protocol may comprise synchronous digital hierarchy, or asynchronous transfer mode (ATM); or a 64 kilobits per second transport protocol. Said transport protocol may comprise synchronous optical network (SONET).
According to a third aspect of the present invention, there is provided in a communications network comprising a plurality of network elements, said network elements comprising a plurality of physical resources organized into a plurality of types of pre-configured structures, a method of providing management data describing available capabilities of said network elements, said method comprising the steps of:
representing a plurality of said physical resources by a set of data templates representations, and
representing said plurality of physical resources by a plurality of reference data, each said reference data referring to a said pre-configured structure and each said reference data referring to at least one said data template representation.
Suitably, each said data template represents a corresponding respective said pre-configured structure type.
A said pre-configured structure may comprise a layered structure, and a said data template may represent said layered structure.
A said pre-configured structure may comprise a layered structure having first and second layers, and a said data template may comprise: a termination point data describing at least one termination point at said first layer of said pre-configured structure; and a set of adaptation rule data describing adaptation rules for adapting between said first layer and said second layer of said pre-configured structure.
A said pre-configured structure may comprise a physical port, and a said data template may represent a physical structure of said physical port.
A said pre-configured structure may comprise a logical port, and a said data template may represent a logical structure of said logical port.
A said reference data may refer to at least one said data template representation by means of a unique reference identifier.
A said data template representation may describe a set of connection capabilities between a plurality of individual said pre-configured structures.
Preferably, each said reference data refers uniquely to a single instance of a said pre-configured structure.
The invention includes a management system for managing a network element comprising a plurality of physical resources arranged into a plurality of pre-configured structures each of a pre-configured structure type, said management system comprising data storage means storing:
at least one data template, said data template representing a said pre-configured structure; and
a plurality of reference data, each said reference data referring to a said pre-configured structure and to at least one said data template.
Specific implementations of the present invention may enable an improved terminology for trail termination points.
In the one implementation according to the present invention, a connection function describing connections between a termination point in a self-layer and one or more termination points within a client layer is provided by means of a set of connection rules, so as to enable description of configurable connections between a plurality of ports.
Further, specific implementations according to the present invention recognize that within a self layer, a trail termination point is always bound to a set of adaptation rules for adapting the self layer of a transport protocol to an adjacent layer of a transport protocol, and that an adaptation of data signals between layers of a transport protocol is always bound to a trail termination point.
By providing a set of rules describing adaptation of data between protocol layers, and by coupling the adaptation rules to a set of rules describing exit and entry to a layer, a concise description of an internal architectural configuration of a network element may be achieved. A plurality of such descriptions may be referenced to each other by means of a set of inter end point connection rules to provide a complete network element template describing functionality capabilities and internal physical constraints of the network element.
Further, specific implementations according to the present invention may provide for inter port connection rules of high complexity, which are configurable per network element.